The problem of obstructed cannon tube bore has occurred ever since cannon tubes were extended forward of the front end of a tank chassis. Presently a round can be fired from a tank without the crew's knowledge that the muzzle end of the cannon is plugged with an obstruction such as mud or sand. Firing the cannon in this condition may result in damaging the muzzle end of the tube so severely that the tube would probably have to be scrapped. Visually checking a bore prior to loading a round in the gun chamber is not a problem. However, once the round has been chambered and the vehicle has been moved to another location, as usually occurs in tactical situations, there is no procedure or device to tell the gunner that the gun bore is unobstructed. Normally when tank crews conduct tactical maneuvers, they check the bore, load the round, close the breech block, then drive to various locations frequently over uneven terrain and fire the round either on the move or sitting stationary. In combat a crew does not have the time to unchamber the round and visually check for obstructions before firing. If along the route the muzzle end of the tube dipped accidentally into a sand berm or mud bank without the tank crew's knowledge, serious damage can occur to the cannon if the crew fires a round under this condition.
Present day cost for a gun tube is approximately $28,000. The present invention is instrumental in reducing the cost for repair or replacement of a cannon damaged as a result of firing a cannon that has been accidentally plugged with obstructive materials.